In the fall of 2020 and spring of 2021 184 photos of cover crops were submited from 7 counties. Photos were taken with a variety of devices, looking straight down from about 5 ft off the ground. In addition, Soil and Water Conservation District employees uploaded information about cover crop planting date, method, species, and previous crop.
The primary analysis we performed was to estimate the green ground cover in each photo, as a metric of cover crop success. A program called Green CovR (https://fgcc-app.github.io/) was used to analyze the % of pixels that were green, i.e. filled by a living cover crop. As seen in the table below, a wide range of cover crop success was was seen across the state. The highest mean and median were seen in Winona County, and lowest in Pipestone.
| county | Minimum | Maximum | Average | Median | Data.Points |
|---|---|---|---|---|---|
| Becker | 0 | 95 | 33 | 37 | 21 |
| East Otter Tail | 0 | 99 | 22 | 15 | 40 |
| Faribault | 3 | 86 | 30 | 22 | 59 |
| Mower | 0 | 94 | 39 | 28 | 22 |
| Olmsted | 4 | 95 | 44 | 41 | 13 |
| Pipestone | 1 | 16 | 7 | 3 | 5 |
| Traverse | 2 | 98 | 26 | 14 | 15 |
| Winona | 9 | 91 | 57 | 66 | 9 |
As Photo 1 demonstrates, some of the low numbers may be due to interference with residue. This method is not a reliable estimate of soil protection for this reason. The % green cover must only be interpreted as a relative indicator of cover crop success. Some research is underway to test factors such as light angle on the ability of the software to detect living cover crops, and to correlate the Green CovR output with actual cover crop biomass. The photo showing 65% green cover also shows that you don't need to get anywhere near 100% to have highly effective ground cover.